CMake: Allow building bundled 3rd party libraries in qtbase

A few things are needed to accomplish that:

- the python scripts do not ignore certain system_foo features anymore
  (it is a hardcoded list for now just to be safe)

- configurejson2cmake now outputs
  qt_find_package(WrapSystemFoo) calls for bundled libraries
  (see below)

- the harfbuzz .pro file is modified to accommodate pro2cmake
  not being able to correctly parse some conditional scopes

- the freetype .pro file is modified to make sure linking of the
  library succeeds without duplicate symbol errors, which qmake
  doesn't encounter due to magical exclusion of cpp files that are
  included in other cpp files (presumably for include moc_foo.cpp
  support)

- feature evaluation for Core, Gui, Network now happens in the
  qtbase/src directory, so that bundled libraries can be conditionally
  built

- for each bundled library there are now two FindWrap scripts:
  - FindWrapSystemFoo which finds an installed library in the system
  - FindWrapFoo which either uses the system installed library or
    the built bundled one depending on a condition

- projects that intend to use bundled libraries need to link against
  WrapFoo::WrapFoo instead of WrapSystemFoo::WrapSystemFoo targets
  (this is handled by pro2cmake).
  Unfortunately manually added qt_find_package(WrapFoo) calls might
  still be needed as is the case for WrapFreetype and others.

- a new cmake/QtFindWrapHelper.cmake file is added that provides
  a macro to simplify creation of WrapFoo targets that link against
  a bundled or system library. The implementation is fairly ugly
  due to CMake macro constraints, but it was deemed better than
  copy-pasting a bunch of almost identical code across all
  FindWrapFoo.cmake files.

- a qtzlib header-only module is now created when using bundled
  zlib, to provide public syncqt created headers for consumers
  that need them. These are projects that have
  'QT_PRIVATE += zlib-private' in their .pro files
  (e.g. qtimageformats, qtlocation, qt3d, etc.)
  This is unfortunately needed due to QtNetwork using zlib
  types in its private C++ API.

The change includes support for building the following bundled
libraries:
- zlib
- libpng
- libjpeg
- Freetype
- Harfbuzz-ng
- PCRE2

The following 3rd party libraries are still using an old
implementation within the CMake build system, and should be migrated
to the new one in the near future:
- double-conversion
- Old harfbuzz

The are a few libraries that are not yet ported:
- system-sqlite
- systemxcb
- maybe others

Among other things, this change allows building qtbase on Windows
without requiring vcpkg.

Task-number: QTBUG-82167
Change-Id: I35ecea0d832f66c1943c82e618de4a51440971a5
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>
Reviewed-by: Leander Beernaert <leander.beernaert@qt.io>

2 files changed, 30 insertions, 2 deletions

diff --git a/src/network/.prev_CMakeLists.txt b/src/network/.prev_CMakeLists.txt
index afe28a2da0..8f38d07e93 100644
--- a/src/network/.prev_CMakeLists.txt
+++ b/src/network/.prev_CMakeLists.txt
@@ -50,7 +50,6 @@ qt_add_module(Network
         kernel
     LIBRARIES
         Qt::CorePrivate
-        ZLIB::ZLIB
     PUBLIC_LIBRARIES
         Qt::Core
     PRIVATE_MODULE_INTERFACE
@@ -147,6 +146,21 @@ qt_extend_target(Network CONDITION QT_FEATURE_http
         socket/qhttpsocketengine.cpp socket/qhttpsocketengine_p.h
 )
 
+qt_extend_target(Network CONDITION QT_FEATURE_system_zlib
+    LIBRARIES
+        ZLIB::ZLIB
+)
+
+qt_extend_target(Network CONDITION NOT QT_FEATURE_system_zlib
+    INCLUDE_DIRECTORIES
+        ../3rdparty/zlib/src
+)
+
+qt_extend_target(Network CONDITION NOT QT_FEATURE_system_zlib AND NOT no_core_dep
+    LIBRARIES
+        Qt::Core
+)
+
 qt_extend_target(Network CONDITION QT_FEATURE_topleveldomain
     SOURCES
         kernel/qtldurl.cpp kernel/qtldurl_p.h
diff --git a/src/network/CMakeLists.txt b/src/network/CMakeLists.txt
index ca30771eb0..c455a00121 100644
--- a/src/network/CMakeLists.txt
+++ b/src/network/CMakeLists.txt
@@ -63,7 +63,6 @@ qt_add_module(Network
         kernel
     LIBRARIES
         Qt::CorePrivate
-        ZLIB::ZLIB
     PUBLIC_LIBRARIES
         Qt::Core
     PRIVATE_MODULE_INTERFACE
@@ -160,6 +159,21 @@ qt_extend_target(Network CONDITION QT_FEATURE_http
         socket/qhttpsocketengine.cpp socket/qhttpsocketengine_p.h
 )
 
+qt_extend_target(Network CONDITION QT_FEATURE_system_zlib
+    LIBRARIES
+        ZLIB::ZLIB
+)
+
+qt_extend_target(Network CONDITION NOT QT_FEATURE_system_zlib
+    INCLUDE_DIRECTORIES
+        ../3rdparty/zlib/src
+)
+
+qt_extend_target(Network CONDITION NOT QT_FEATURE_system_zlib AND NOT no_core_dep
+    LIBRARIES
+        Qt::Core
+)
+
 qt_extend_target(Network CONDITION QT_FEATURE_topleveldomain
     SOURCES
         kernel/qtldurl.cpp kernel/qtldurl_p.h